It is well known that the secondary of an ignition coil produces a very high voltage to enable an electric arc to be generated between the electrodes of the spark plugs, so as to ignite the fuel/air mixture in the cylinders of the engine. Conventionally, all of the spark plugs are controlled from a single, common ignition coil through, for example, a mechanical distributor which is generally of the rotating arm type. A bundle of high tension cables is required in order to connect the secondary of the ignition coil to the distributor and to connect the distributor to each of the spark plugs.
Apart from the cost of the high tension cable bundle, the latter gives rise to electrical losses which produce parasotic radio waves. These may be acceptable if the distributor is of the mechanical type, but, where the ignition system is of the electronic type, the radio waves give rise to substantial perturbation in the ignition system itself.
In order to overcome these disadvantages, it has already been proposed to provide a separate ignition coil for each spark plug. Such an individual ignition coil, which may be referred to as a monocylinder coil, may comprise, in a known manner, a closed magnetic circuit assembly comprising a central magnetic core, around which two winding spools of plastics material are arranged coaxially, with primary and secondary windings being carried on the winding spools, and with this assembly being integrated into a housing which is formed by being moulded in plastics material around the magnetic circuit assembly. Synthetic resin is flowed into the interior of the housing so as to encaptulate the various elements of the ignition coil and to insulate them electrically from each other. The present invention is directed specifically to a monocylinder coil of this type.
In such a coil, the primary winding has to be supplied with low tension voltage. The low tension supply means are generally situated on the upper part of the ignition coil itself, and comprise connecting strips, one end of which is connected to the primary winding, by soldering or by any other means, with the other ends being located in the body of a connector. This connector is fixed on the body of the ignition coil, and provides the low tension electrical connection between the latter and the outside.
The angular orientation of this connector has to be determined according to the design of the particular vehicle in which the ignition coil is installed. In addition the connector may be of any one of a number of different forms, so that it is adapted to fit the design requirements of the particular vehicle concerned. The manufacturer of the ignition coil must therefore be prepared to provide a wide variety of different designs of connector in order to satisfy the requirements of his customers, the automobile manufacturers.
For obvious cost reasons, it is essential that the housing and the other components of the magnetic assembly should remain identical to each other regardless of the type of connector employed.
In addition, the electrical connections between the ends of the connecting strips and the ends of, in particular, the primary winding should be made before the magnetic assembly is introduced into the housing.